The leak has also cost factories in the industrial complex about 17.7 billion won (US$15.9 million) in lost production, prompting calls for emergency help from the central government.

A team of government inspectors visited the site last Friday and announced its decision to designate the scene as a special disaster zone after a meeting with officials.

Under law, a special disaster area is entitled to extra financial aid from the government.

"Last week''s examination showed the damage is presumed to be too extensive for the local government to handle on its own," said Yook Dong-han, the vice minister of the Prime Minister’s Office. "The government will make detailed measures and standards to administer support, and plans to carry out another round of in-depth inspections into the region as early as possible," he added.